2. Field of the Invention
The present invention relates to electric blankets.
2. Description of the Prior Art
A typical type of conventional electric blankets includes, as shown in FIG. 5 of the accompanying drawings, a blanket proper 3 having disposed therein an electric heater 1 and temperature detecting means 2 for detecting the temperature of the electric heater 1, temperature setting means 4 for presetting the electric heater 1 to a desired temperature, a preheating switch 8 for starting a preheating operation at a higher temperature setting, a timer 9, setting changing means 6 for restoring the higher temperature setting to the temperature preset by the temperature setting means 4 when the time set by the timer 9 is reached and control means 7 responsive to the temperature detected by the temperature detecting means 2 and a signal from the setting changing means 6 to control the flow of current to the electric heater 1. (For example, Japanese Utility Model Publication No. 48-8176 discloses an electric blanket of the same purport).
With this conventional construction, too much operation is required since it is necessary to turn on the preheating switch 8 and set the timer 9 to the desired time before going to bed and it is not infrequent for the user to forget the setting of the preheating switch 8. Also, the user does not always go to bed at the timer-set time. If the user retires earlier than the timer-set time, the higher temperature setting remains as such and the timer setting must be done all over again thus requiring too much operation. Going to bed without doing the timer setting all over again has the disadvantage of overheating and making the user to feel uncomfortable. Also, if one who has gone to bed rises to go to the toilet, for example, his temperature decreases and he feels cold soon after going to bed again. Then, not only the scale setting must be raised to increase the blanket temperature but also the scale setting must be restored to the initial setting as soon as he gets warm thus requiring too much operation and he frequently falls asleep without restoring the scale setting thus feeling uncomfortable due to the heat while sleeping.